I am having trouble using learn mode on some of my plug-ins...

The Learn function in Automap relies on plug-ins sending automation data when a control is moved on the GUI with the mouse.

If the plug-in does not send the appropriate automation data then you will need to use an alternative way to learn the controls.

This can be done one of two ways;

If your host application allows you to view the controls of a plug-in without using the plug-ins own GUI you can learn the controls using this alternative view. (Logic and Ableton Live both allow you to do this)

You can use the controller itself to learn controls. If the parameter you wish to assign is already mapped to a different control on your Automap controller, simply tweak the parameter using the 'old' control, then click the 'Learn' button on the Automap GUI and move the 'new' control that you wish to assign the parameter to.

If neither of these methods work, you should be able to manually assign the parameter to a control in the Automap > Mixer/plug-in mappings page by selecting the relevant plug-in and selecting 'Edit mapping'. If you select a control, you'll be able to use the 'Edit Assignment' section at the bottom of the edit mapping page to assign a parameter from the list to it.